The present invention relates generally to a piston machine, and more particularly to a piston machine wherein a piston is connected with a piston-reciprocating element by a glide shoe articulated to the piston and in gliding contact with a glide surface of the piston-reciprocating element.
Piston machines are known of the type having a housing, a reciprocable piston in the housing, and provided with an axial end portion, and a piston-reciprocating element having a glide surface located opposite to and movable with reference to the end portion of the piston for effecting reciprocation of the latter. It is also known to provide a glide shoe which is connected with the axial end portion of the piston and has a glide face which is in gliding contact with the glide surface of the piston-reciprocating element. Such arrangements are known both in axial piston machines and in radial piston machines, the present invention being particularly concerned with the latter type. Such a radial piston machine is disclosed e.g. in the U.S. Pat. No. 3,663,125.
It is known to construct the glide shoe with an annular recess in its glide face, the recess being surrounded by a relatively broad sealing rim, and the glide face being further provided on its corners with approximately triangular supporting face portions. This prior-art construction assures, due to the presence of the broad sealing rim, that there will be low leakage losses of fluid and that the glide face will be relatively resistant to wear. However, this construction has the disadvantage that the hydrostatic relief of the glide shoe is relatively poor because the supporting face portions are too small to allow the development of significant hydrodynamic pressure fields between themselves and the juxtaposed glide surface of the piston-reciprocating element. This means that this type of glide shoe is not useable for radial piston machines which are operated at high pressures or at high speeds of revolution.